1. Field of the Invention
This invention relates to an appliance programmer and is more particularly concerned with safety circuits to prevent overfilling and subsequent flooding of the appliance as well as other malfunctions of the appliance.
2. Description of the Prior Art
United States Letters Pat. No. 3,774,056 discloses a programmer for an appliance, in particular a dishwasher, in which a water level sensor is directly connected to the control logic circuit and provides for delay in the clock cycle while the tub is being filled. In addition if water continues to enter the vat after a fill event is completed, the overfill protection logic locks the control logic circuit into the pump-out cycle. Mechanical failures of the water valve solenoids, failure of the control logic or failure of the interfacing devices will eventually show up in that water is present in the tub, whereupon the overfill protection logic will cause the control logic to enter the pump-out cycle. At the same time the first wash light is caused to blink continuously thus calling attention to the fact that a failure has occurred. However, this patent does not disclose the simultaneous direct connection of the water level sensing switch to both the water fill valve solenoid and the control circuit. In addition, it does not show the use of an overfill protection circuit including a counter wherein, when an insufficient water level is detected during a washing operation, the water fill valve can be actuated a predetermined number of times to bring the water in the vat up to a desired level after which the program is interrupted and a service light is energized.
United States Letters Pat. Nos. 3,477,258 and 3,707,856, both of which are assigned to Whirlpool Corporation the assignee of record in the present application, show electronic programmers for automatic washing machines which include water level sensors.